Manufacture of material suitable for receiving writings by electrodecomposition



Patented July 18, 1933 UNITED STATES PATENT OFFICE RICHARD SCHMIDT, OF DESSAU IN ANHALT, GERMANY, ASSIGNOR TO AGFA ANSCC CORPORATION, OF BINGHAMTON, NEW YORK, A CORPORATION-OF NEW YORK MANUFACTURE OF MATERIAL SUITABLE FOR RECEIVING WRITINGS BY ELECTRODECOMPOSI'IION No Drawing. Application filed October 15, 1929,.s xiarfno...ssa,esa, and in Germany October 16, 1928.

The present invention relates to a process of manufacturing material suitable of receiving writings by electro-decomposition; more particularly it relates to a processof impregnating a suitable support with a specific soluton of heavy metal salts and to the material obtainable by that process.

If paper, a textile fabric or another suitable support is treated with heavy metal salts capable of forming a sulfide and with .a salt which by cathodic reduction evolves hydrogen sulfide, is brought in contact with a current-conducting electrode, a heavy metal sultide is produced at the point of contact. Colored characters can thus be produced upon the paper. The papers, textile fabrics, or the like, impregnated according to the hitherto known processes of this kind,'possess, however, no suflicient stability. Moreover, the impregnating liquors hitherto used are stable only for a short time.

I found, that materials capable of receiving writings by elcctro-dec'nnposition and of excellent stability can be prepared by mpregnating paper, a textile fabric or another suitable support with a weakly: acid aqueous solution of douhlesalts of heavy metal salts with alkalimetal thiosulfate or sodium sulfite. Preferably, I .may use for the. said purpose a plmtographie acid fixing bath solution which has already been used. The sa d used fixing bath solutions contain probably silver double salts of the formula [Ag S203) 1Na or [A 0 Na and a solution of a silver halide in alkali b1 sulfite. The material treated with such a solution is then dried in a current of'hot air.

graphic process, namely a waste product, the

costs of the preparation of papers, textile fabrics, or the like to be electrolytically written on are very much reduced. The process can be rendered still cheaper by recovering the silver from the said fixing bath solution before impregnating the paper with the solution. For this purpose there is added in known-manner an excess of finely subdivided metal which is not a precious metal like silver,

for instance lead. If fixing baths thus treated support with an acid aqueous solution containing a thiosulfate of the group consisting of an alkalimetal thiosulfate and ammonium thiosulfate, and a heavy metal salt capable of forming a double salt with said thiosuli'ales, and drying the material.

2. The process of manufacturing material for receiving writings by, electrolytic decomposition which consists in impregnating a. support with an acidfixing bath comprising a thiosulfate of the group consisting of an alkalimetal thiosulfate and ammonium thiosulfate, and an alkalimetal bisultite, said fixing bath having already been used in the photographic process, and drying the material. 1

3. The process which comprises treating an acid fixing bath comprising a thiosulfate' of the group consisting of an alkalimetal thiosulfate and ammonium thiosulfate, and

sodium bisulfate, said fixing bath having already be'en used in the photographic process, wlth a heavy metal capable of forming a double salt with said thiosulfates in finely subdivided form, filtering off the solution thus Obtained, im ')regnating a support with said filtered ofl' solution, and drying said impregnated support.

.4. The process which comprises treating an acid fixing bath comprising a thiosulfate of the group conslstlng of an alkalimetal thiosulfate and ammonium thlosulfate, and

sodium bisulfite; said fixing bath having al-- ready been used in the photographic fprocess, with lead in finely subdivided form, ltering off the solution thus obtained, impregnating a support with said filtered ofl' solution, and

drying said impregnated support;

5. A material capable of receiving writings by electrolytic decomposition consisting of a support impregnated with a double salt of a thiosulfate of the group consisting of RICHARD SCHMIDT. 

